<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>逻辑与</title>
</head>

<body>
  <script>
    let o = {
      x: 1
    }
    let p
    console.log(p || o);

    let a = [1, 2, 3]
    let i = 0
    console.log(a[i++] *= 2);
    console.log(i);
    console.log(a[i++] = a[i++] * 2);
    console.log(a);

    let b = [1, 2, 3]
    let j = 0
    console.log(b[j++] = b[j++] * 2);
    console.log(b);


  </script>
</body>

</html>